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TEMPER COLORS 


Deg. F. 


Normal 


430° F. 


450° F. 


475° F. 


500° F. 


525° F. 


550° F. 


575° F. 


600° F. 


625° F. 


650° F. 


COLOR 


Bright Steel 


Light Yellow 


Medium Yellow 


Dark Yellow 


Brown Yellow 


Light Purple 


Dark Purple 


Dark Blue 


Peacock Blue 


Peacock Green 


Gray Gr^en 

©Cl. A 4 57882 


Oxide Tint 








SUGGESTED USES 


HARDEN—THEN DRAW TO TEMP. SHOWN 


r Rub surface bright, the necessary con- 
} dition for observing temper colors, as 
v. they appear, while drawing. 

( Tools for cutting hard metals at slow 
| speed, scrapers, etc. 

Lathe and planer tools, boring cutters, 
milling cutters, twist drills, taps, thread¬ 
cutting tools, etc. 

Stud-bolt taps, small cutting tools, cold 
chisels for hard cutting, etc. 

Various kinds of punches, dies, stone 
drills, mill picks, file cutters, cold chisels 
for cast iron, etc. 

Shear knives, punches, track tools, rivet 
sets, cold sets, hammers, boiler-makers 
tools, etc. 

Blacksmith tools, battering tools re¬ 
quired to be both hard and tough, axes, 
C etc. 

Springs, gears, hot chisels, screw driv¬ 
ers, cold chisels for soft work, etc. 

Use for any purpose, in case next lower 
temper color makes the tool slightly too 
hard. 

Use for any purpose, in case next lower 
temper color makes the tool slightly too 
hard. 

Use for any purpose, in case next lower 
temper color makes the tool slightly too 

hard ‘ APR -9 1917 


1 


Copyright <<?n by j 






I . 


METHODS OF TEMPERING 


TEMPERING 

The terms tempering, drawing, or letting down 
refer to a process of softening hardened steel. 

Tools should be temper - drawn to the proper 
point as soon as possible after hardening, to avpid 
cracking. 

. ■■■■■■ . . 11 n .. 


COL O R METHOD OF TEMPERING 

Iron oxide will form on the polished surface 
of heated steel, open to the air, varying in color 
relative to the degree of heat applied. (Refer to 
Temper Color Chart.) y 

There are several methods of drawing the tem¬ 
per by color, as follows: 

Drawing — by letting down the heat from the 
shank of the tool, after hardening the point, and 
quenching in water, when proper color is reached. 

Drawing—in a heated sand bath. 

Drawing—on a heated steel plate. 

--- ,| - 


HOT OIL OR LEAD BATH FOR TEMPERING 

The most reliable method is to temper-draw in 
hot oil or lead. 

Oil is suitable up to 500° F. 

Mixture of 14 parts lead to 8 parts tin can be 
used up to the highest heat required. (Melts at 
420° F.) 

For oil or lead tempering, heat the bath to de¬ 
gree of temperature required for proper drawing. 
(Refer to Chart.) 

.. 11 — 11 ... 


REMARKS ON TEMPERING 

It is impossible to apply a rigid rule for temper¬ 
ing which will offset all the variables that may be 
present in any operation, such as— 

Variation in carbon in any grade of steel, likely 
to be from 15 to 20 points range. 

Variation in temperature at which steel is 
hardened. 

Variation in temperature of the quenching me¬ 
dium, section of tool, etc. 


II 


II 


PROPER ADJUSTMENT 

After tempering, if tool is too brittle, redraw at a 
higher temperature. 

If too soft, reharden and draw at a lower tem¬ 
perature. 


V. S. YARNALL, 1917 

















































































